/*========================== begin_copyright_notice ============================

Copyright (C) 2018-2021 Intel Corporation

SPDX-License-Identifier: MIT

============================= end_copyright_notice ===========================*/

#define DEBUG_TYPE "gen-simplification"
#include "Compiler/CISACodeGen/FixupExtractValuePair.h"
#include "Compiler/CISACodeGen/ShaderCodeGen.hpp"
#include "Compiler/CISACodeGen/TranslationTable.hpp"
#include "Compiler/CISACodeGen/WIAnalysis.hpp"
#include "Compiler/CodeGenContextWrapper.hpp"
#include "Compiler/MetaDataUtilsWrapper.h"
#include "Compiler/IGCPassSupport.h"

#include "common/LLVMWarningsPush.hpp"
#include <llvm/Pass.h>
#include <llvm/IR/InstVisitor.h>
#include <llvm/IR/Instruction.h>
#include "common/LLVMWarningsPop.hpp"

using namespace llvm;
using namespace IGC;
using namespace IGC::IGCMD;

namespace {

class ExtractValuePairFixup : public FunctionPass {
public:
  static char ID;

  ExtractValuePairFixup() : FunctionPass(ID) { initializeExtractValuePairFixupPass(*PassRegistry::getPassRegistry()); }

  bool runOnFunction(Function &) override;

  void getAnalysisUsage(AnalysisUsage &AU) const override {
    AU.setPreservesCFG();
    AU.addPreservedID(TranslationTable::ID);
    AU.addPreservedID(WIAnalysis::ID);
    AU.addRequired<CodeGenContextWrapper>();
    AU.addRequired<MetaDataUtilsWrapper>();
  }

private:
  bool fixup(Function &F) const;
};

} // End anonymous namespace

char ExtractValuePairFixup::ID = 0;

#define PASS_FLAG "igc-extractvalue-pair-fixup"
#define PASS_DESC "Fixup extractvalue pairs"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS false
namespace IGC {
IGC_INITIALIZE_PASS_BEGIN(ExtractValuePairFixup, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
IGC_INITIALIZE_PASS_DEPENDENCY(CodeGenContextWrapper)
IGC_INITIALIZE_PASS_DEPENDENCY(MetaDataUtilsWrapper)
IGC_INITIALIZE_PASS_END(ExtractValuePairFixup, PASS_FLAG, PASS_DESC, PASS_CFG_ONLY, PASS_ANALYSIS)
} // namespace IGC

FunctionPass *IGC::createExtractValuePairFixupPass() { return new ExtractValuePairFixup(); }

bool ExtractValuePairFixup::runOnFunction(Function &F) {
  // Skip non-kernel function.
  MetaDataUtils *MDU = nullptr;
  MDU = getAnalysis<MetaDataUtilsWrapper>().getMetaDataUtils();
  auto FII = MDU->findFunctionsInfoItem(&F);
  if (FII == MDU->end_FunctionsInfo())
    return false;
  // Fixup pairs of extractvalue.
  return fixup(F);
}

bool ExtractValuePairFixup::fixup(Function &F) const {
  bool Changed = false;
  // Find 'extractvalue' and pull them just after the definition of their
  // aggregation source.
  for (auto &BB : F) {
    for (auto BI = BB.begin(), BE = BB.end(); BI != BE; /*EMPTY*/) {
      auto EVI = dyn_cast<ExtractValueInst>(&*BI++);
      if (!EVI)
        continue;
      Instruction *I = dyn_cast<Instruction>(EVI->getAggregateOperand());
      if (!I || I->getParent() != EVI->getParent())
        continue;
      auto II = I->getIterator();
      for (++II; II != BI; ++II) {
        if (isa<ExtractValueInst>(II))
          continue;
        // Move this 'extractvalue' just after the aggregate value.
        EVI->moveBefore(BB, II);
        Changed = true;
        break;
      }
    }
  }
  return Changed;
}
